The production of gas products rich in hydrogen by reforming of hydrocarbons is well established in industry. The obtained reformate, known as "synthesis gas", contains in addition to hydrogen, carbon dioxide and carbon monoxide; and includes varying amounts of one or more other components, such as methane, nitrogen and argon. Various methods have been devised for separation and recovery of hydrogen from the reformate and for the recovery of either or both carbon monoxide and carbon dioxide substantially free of accompanying contaminants.
The more conventional industrial processes for production of these hydrogen-rich gas products employ as starting material natural gas or other methane-rich hydrocarbon stream which is charged to a steam-methane reformer under conditions producing an effluent made up largely of hydrogen, carbon monoxide and carbon dioxide. In the conventional "state of the art" technology, the process gas is cooled to separate out water by condensation and CO.sub.2 is removed by solvent extraction with monoethanolamine (MEA), carbonate solution or other CO.sub.2 absorbent liquid. The CO.sub.2 -freed remainder is dried and compressed, then subjected to a cryogenic unit, so-called "cold box", wherein the gas is cooled to effect separation of hydrogen from CO/CH.sub.4, and a high purity CO stream (.about.99.6% pure) is recovered. The hydrogen stream leaving the cold box (98% pure H.sub.2) is further purified by pressure swing adsorption (PSA) from which there is obtained a substantially pure product (.about.99.9% H.sub.2).
In certain known operations, reforming of a hydrocarbon stream for hydrogen production is carried out in a two-stage operation wherein primary steam reforming is followed by a secondary reforming with air or oxygen.